I also remember that Pingue from AC-Web started development on a CMS some time I go but I imagine they quit. It is still available though, but I believe it is still in beta (and won't get through it). Try google PingueCMS if you're interested. (I recommend having some knowledge regarding php/html/css if you're thinking to use it, cause it definetly needs some tweaking if it hasn't gotten past the last release I tried).

There is of course Arc-Cms as well, but I have no information regarding it.

There are also a great deal other web templates (not CMS though) with a wow theme to it. I'll help you find some if the above is not for you, or you can simply try different search combinations on google, I'm sure you'll find something.

PS: If you wish to learn and are really interested in the battle.net site, then you could HTTRack it and try to develop something on your own! :-)